The effectiveness of fulvestrant was established by
comparison to the selective aromatase inhibitor anastrozole, as measured by
objective response rate and time to progression. The objective response rate in
the North American trial was 17% with fulvestrant vs 17% with anastrozole, and
in the European trial, 20% with fulvestrant vs 15% with anastrozole. The
reported time to progression for fulvestrant vs anastrozole was 5.5 vs 3.5
months in the North American trial, and 5.5 vs 5.2 months in the European trial.
Fulvestrant can cause fetal harm when administered to a
pregnant woman. Women of childbearing potential should be advised not to become
pregnant while receiving fulvestrant.
Adverse Reactions Noted
The most commonly reported adverse events seen with fulvestrant vs
anastrozole treatment, regardless of the investigator’s assessment of
causality, were gastrointestinal symptoms (nausea, 26.0% vs 25.3%; vomiting,
13.0% vs 11.8%; constipation, 12.5% vs 10.6%; diarrhea, 12.3% vs 12.8%;
abdominal pain, 11.8% vs 11.6%), headache (15.4% vs 16.8%), back pain (14.4% vs
13.2%), hot flushes (17.7% vs 17.3%), and pharyngitis (16.1% vs 11.6%).
Injection site reactions of mild, transient pain and inflammation were reported
in 7% of patients (1% of treatments) given single 5-mL injections and 27% of
patients (4.6% of treatments) given 2 × 2.5-mL injections of fulvestrant.